1. Field of the Invention
The invention relates to a fuel cell, and a separator that constitutes the fuel cell. In particular, the invention relates to the supply and discharge of reactant gases.
2. Description of the Related Art
Fuel cells, for example, a solid polymer fuel cell, convert chemical energy of substances directly into electric energy by supplying reactant gases (a fuel gas containing hydrogen, and an oxidizing gas containing oxygen) to two electrodes (a fuel electrode and an oxygen electrode) that face each other across an electrolyte membrane so as to cause electrochemical reactions. A known major structure of such fuel cells is a so-called stack structure in which laminate members that include generally platy electrolyte membranes are stacked alternately with separators, and are fastened together in the stacking direction.
A known fuel cell having a stack structure incorporates separators having internal channels that are substantially perpendicular to the thickness direction (e.g., Japanese Patent Application Publication No. 5-109415 (JP-A-5-109415)). In such a fuel cell, the internal channels of the separators are used to supply the reactant gases to or discharge them from the electrodes. In such separators, the aforementioned internal channels are formed by stacking three plate members. An end of such an internal channel links in communication to a reactant gas manifold that penetrates through the separator in the thickness direction, and another end of the internal channel reaches an electrode-facing surface of the separator. Via such internal channels, the reactant gases are transferred between the reactant gas manifolds and the electrodes.
However, in the foregoing related art, an internal channel for one of the two reactant gases, that is, the oxidizing gas, is provided along opposite two sides of the four sides of a generally rectangular power generation region, and a channel for the other reactant gas, that is, the fuel gas, is provided along the other two sides. Therefore, in the power generation region, the oxidizing gas and the fuel gas flow in directions that are both planar directions of the electrolyte membrane and that intersect with each other. This flowage of the reactant gases does not necessarily provide good power generation performance. Thus, a flowage thereof that provides better power generation performance is desired to be realized.